Semiconductor contact via structure having amorphous silicon side walls

A contact structure for an integrated circuit, comprising:

• an underlying conductive structure;
• a first conformal oxide layer overlying the underlying conductive structure, such first conformal oxide layer being undoped or lightly doped;
• a planarizing oxide layer overlying the first conformal oxide layer, such planarizing oxide layer having a large amount of impurities;
• a second conformal oxide layer, such second conformal oxide layer being undoped;
• an opening through the second conformal oxide layer, the planarizing oxide layer, and the first conformal oxide layer to expose a portion of the underlying conductive structure;
• thin sidewalls of amorphous silicon alongside sides of the opening, separating the opening from the first and second conformal oxide layers and the planarizing oxide layer;
• and
• a conductive interconnect layer lying on the second conformal oxide layer and extending into the opening, and separated from the planarizing oxide layer and the first and second conformal oxide layers in the opening by the thin amorphous silicon sidewalls.